I had a chance to take a look at an outdated crackshield's source code; What I can tell you is, it's not simple.
What you are trying to do requires deep knowledge in computer system.
I suggest you to look for updated crackshield rather than trying to fix it yourself.
The latest version of crackshield has been updated on 05/19/2013 and you can get it

.
However, I don't know if this would work with Taiwanese Mabinogi (This one doesn't work with Korean Mabinogi at the moment) and if it doesn't work, I suggest you to contact yiting2002 at yydzh.com and ask him/her for help.